A storage disk cartridge, particularly for a magnetic storage disk, typically comprises an external shell encasing the storage disk, a head access aperture in the shell for enabling a head to be moved into position with respect to the disk, a shutter mounted to the shell to appropriately cover or expose the aperture, and a spring that biases the shutter to cover the aperture.
In many instances, the spring is a torsion spring having one arm attached to the shell and the other arm attached to the shutter. As is known, the operative portion of such a torsion spring comprises a generally helical coil of wire wound around an axis, where loading and unloading of such torsion spring causes circumferential rotation of the windings of such coil about such axis. Such torsion spring is typically positioned in the interior of a disk cartridge along with the storage disk such that the axis of the helical coil and the axis of the disk are generally parallel. While torsion springs have been found to work acceptably in general, several problems have been identified.
Firstly, to fit a torsion spring into the available space inside a disk cartridge while at the same time keeping stresses relatively low, such torsion spring must have a relatively large radius for the helical coil and a relatively small number of windings in such helical coil. Such constraints limit the number of torsion spring designs that are viable, especially when the available space inside the disk cartridge is confined. Morever such viable designs may not be optimal in terms of reliability or case of manufacture and/or assembly. Secondly, in a torsion spring, the coil windings in the helical coil must be free to individually circumferentially rotate during loading and un-loading. As a result, the helical coil cannot be over-molded with a protective covering. Thirdly, automated manufacturing and/or assembling of springs becomes more difficult as the radius of the spring helical coil increases. In particular, the coil windings tend to tangle more as the radius of the helical coil increases.
Accordingly, a need exists for a storage disk cartridge having an alternative type of spring biasing the cartridge shutter to cover the cartridge aperture.